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Scientists in Germany Draft Neanderthal Genome

Scientists report that they have reconstructed the genome of Neanderthals, a human species that was driven to extinction some 30,000 years ago, probably by the first modern humans to enter Europe.

The Neanderthal genome, when fully analyzed, is expected to shed light on many critical aspects of human evolution. It will help document two important sets of genetic changes: those that occurred between 5.7 million years ago, when the human line split from the line leading to chimpanzees, and 300,000 years ago, when Neanderthals and the ancestors of modern humans parted ways; and second, the changes in the human line after it diverged from Neanderthals.

An early inference that can be drawn from the new findings, which were announced Thursday in Leipzig, Germany, is that there is no significant trace of Neanderthal genes in modern humans. This confounds the speculation that modern humans could have interbred with Neanderthals, thus benefiting from the genes that adapted the Neanderthals to the cold climate that prevailed in Europe in last ice age, which ended 10,000 years ago. Researchers have not ascertained if human genes entered the Neanderthal population.

Possessing the Neanderthal genome raises the possibility of bringing Neanderthals back to life. Dr. George Church, a leading genome researcher at the Harvard Medical School, said Thursday that a Neanderthal could be brought to life with present technology for about $30 million.

Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig led a team that had to overcome daunting technical obstacles to produce the draft of the Neanderthal genome. He was assisted by the company 454 Life Sciences, which invented a new DNA decoding machine that works by analyzing millions of very small fragments of DNA in parallel. DNA from Neanderthal bones is fragmented in just this way.

Dr. Pääbo began his project more than 10 years ago, when he succeeded in extracting the first verifiable piece of Neanderthal DNA. Most Neanderthal bones have no recoverable DNA and those that do are heavily contaminated with modern human DNA from the many scientists and curators who handled them. Distinguishing human and Neanderthal DNA is hard because they are so similar.

He said at a news conference in Leipzig on Thursday that he now had retrieved usable DNA from six Neanderthals and analyzed 3.7 billion units of DNA. The Neanderthal genome, like that of modern humans, is 3.2 billion units in length. Because many units have been analyzed several times over, and many not at all, Dr. Pääbo can now see about 63 percent of the Neanderthal genome. He will continue to analyze it until he has accumulated the equivalent of 20 Neanderthal genomes, which will allow almost every unit to be accurately known.

An earlier analysis of Neanderthal DNA by Dr. Pääbo proved to have had 10 percent human contamination, he said, but in the new draft genome, he has taken pains to measure the degree of human contamination and finds it is below 3 percent, he said.

Archaeologists have long debated whether Neanderthals could speak, and they have eagerly awaited Dr. Pääbo’s analysis of the Neanderthal FOXP2, a gene essential for language. Modern humans have two changes in FOXP2 that are not found in chimpanzees, and that presumably evolved to make speech possible. Dr. Pääbo said Neanderthals had the same two changes in their version of the FOXP2 gene. But many other genes are involved in language, so it is too early to say whether Neanderthals could speak.

Dr. Richard Klein, a paleoanthropologist at Stanford University, said Dr. Pääbo’s project was “incredibly exciting” and could eventually shed light on the behavioral differences between Neanderthals and modern humans.

When the full Neanderthal genome is in hand, could it be made to produce the living creature its information specifies? Ethical considerations aside, Dr. Pääbo said, Neanderthals could not be generated with existing technology. Dr. Church of Harvard disagreed. He said he would start with the human genome, which is highly similar to that of Neanderthals, and change the few DNA units required to convert it into the Neanderthal version.

This could be done, he said, by splitting the human genome into 30,000 chunks about 100,000 DNA units in length. Each chunk would be inserted into bacteria and converted to the Neanderthal equivalent by changing the few DNA units in which the two species differ. The changed lengths of DNA would then be reassembled into a full Neanderthal genome. To avoid ethical problems, this genome would be inserted not into a human cell but into a chimpanzee cell.

The chimp cell would be reprogrammed to embryonic state and used to generate, in a chimpanzee’s womb, a mutant chimp embryo that was a Neanderthal in many or most of its features.

Dr. Church acknowledged that ethical views on such an experiment would vary widely. But bringing a Neanderthal to birth, he said, would satisfy the human desire to communicate with other intelligences.

Dr. Church said he had no plans for such an experiment, but if someone were eager to supply the financing, “We might go along with it.” The treatment of Neanderthals would raise many problems. “Are you going to put them in Harvard or in a zoo?” asked Dr. Klein of Stanford.

A version of this article appears in print on , on page A12 of the New York edition with the headline: Neanderthal Genome Hints at Language Potential but Little Human Interbreeding. Order Reprints|Today's Paper|Subscribe